Page 77 - DCAP402_DCAO204_DATABASE MANAGEMENT SYSTEM_MANAGING DATABASE

Database Management Systems/Managing Database

Notes 4.8 Self Assessment

Fill in the blanks:
1. You can combine different query blocks into a single query expression with the
.............................. operator.
2. A subquery is always a single query block .............................. that can contain other subqueries
but cannot contain a UNION.

3. A view can be dropped using a .............................. statement.
4. .............................. are useful for security of data.
5. .............................. are used to query data from two or more tables, based on a relationship
between certain columns in these tables.
6. An .............................. cannot be nested inside a Left Join or Right Join.
7. .............................. combines two tables based on their common columns.

8. Subqueries are similar to SELECT ..............................
9. The .............................. clause should follow the GROUP BY clause.
10. A query inside a query is called as .............................. query.

4.9 Review Questions

1. Create a table with five columns and apply subqueries concept on that table.
2. You already create a table in question no. 1, then apply SQL IN concept on that table with
suitable example.
3. What do you mean by ORDER BY clause? Apply this clause with a suitable example.
4. Explain UNION clause in detail with the help of example.

5. How will you drop views? Explain with suitable example.
6. What is the purpose of joins in SQL? Explain inner join.
7. Create a table name student with five important column and apply order by and having
clause on it.
8. What do you mean by complex queries?
9. How will you drop a view? Explain with example.

10. Distinguish between left and right joins.
Answers: Self Assessment

1. union 2. (Select)
3. drop 4. Views
5. SQL joins 6. inner join
7. Natural join 8. chaining

9. having 10. nested

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